Practical guides and deep dives on .NET, C#, PostgreSQL, software architecture and AI.https://ivankahl.com/enhttps://ivankahl.com/blog/practical-guide-to-modeling-business-processes-in-rest-apis/https://ivankahl.com/blog/practical-guide-to-modeling-business-processes-in-rest-apis/Five patterns for modeling complex business processes in REST APIs, from nesting sub-resources to accepting RPC-style verbs when CRUD falls short.Mon, 23 Mar 2026 00:00:00 GMTRESTAPI DesignArchitecturehttps://ivankahl.com/blog/8-ndepend-rules-to-enforce-domain-driven-design-in-dotnet/https://ivankahl.com/blog/8-ndepend-rules-to-enforce-domain-driven-design-in-dotnet/Eight NDepend CQLinq rules automate Domain-Driven Design enforcement in .NET, protecting architectural boundaries, entities, and aggregate roots.Thu, 12 Mar 2026 00:00:00 GMT.NETDomain-Driven DesignStatic AnalysisNDependC#https://ivankahl.com/blog/decompiling-the-new-csharp-14-field-keyword/https://ivankahl.com/blog/decompiling-the-new-csharp-14-field-keyword/The IL code behind the C# 14 field keyword reveals how it removes property boilerplate, and which caveats matter before refactoring an existing codebase.Wed, 17 Dec 2025 00:00:00 GMTC#.NET 10Guideshttps://ivankahl.com/blog/csharp-dispose-pattern/https://ivankahl.com/blog/csharp-dispose-pattern/Reliable resource management in C# depends on IDisposable. Implementing it correctly cleans up unmanaged resources like file handles and connections, and prevents leaks.Mon, 13 Oct 2025 00:00:00 GMTGuidesC#.NET.NET Corehttps://ivankahl.com/blog/stop-spaghetti-sql-simplify-complex-queries-with-postgres-ctes-in-supabase/https://ivankahl.com/blog/stop-spaghetti-sql-simplify-complex-queries-with-postgres-ctes-in-supabase/Postgres common table expressions break tangled queries into clear, named steps. A music streaming app on Supabase demonstrates how much more readable they become.Thu, 02 Oct 2025 00:00:00 GMThttps://ivankahl.com/blog/csharp-14-null-conditional-assignments/https://ivankahl.com/blog/csharp-14-null-conditional-assignments/C# 14 adds null-conditional assignment, a feature that safely assigns values to properties or indexers without long chains of if statements.Wed, 10 Sep 2025 00:00:00 GMTGuidesC#.NET 10.NEThttps://ivankahl.com/blog/csharp-14-user-defined-compound-assignments/https://ivankahl.com/blog/csharp-14-user-defined-compound-assignments/C# 14 lets types define their own compound assignment operators, avoiding unnecessary object creation. The feature is explained along with the pitfalls to avoid.Mon, 04 Aug 2025 00:00:00 GMT.NET.NET 10GuidesC#https://ivankahl.com/blog/google-gemini-receipt-parser-for-ynab/https://ivankahl.com/blog/google-gemini-receipt-parser-for-ynab/Logging expenses in YNAB by hand is tedious. A Docker-based service now uses Google Gemini to read receipt images and import and categorise transactions automatically.Thu, 16 Jan 2025 00:00:00 GMThttps://ivankahl.com/blog/beyond-the-random-class-cryptographic-randomness-in-net-6/https://ivankahl.com/blog/beyond-the-random-class-cryptographic-randomness-in-net-6/Security-sensitive code needs true randomness. Here, .NET's RandomNumberGenerator class is used to produce cryptographically secure random values instead of Random.Mon, 06 Jan 2025 00:00:00 GMTGuidesC#.NET.NET 6Securityhttps://ivankahl.com/blog/csharp-null-conditional-and-null-coalescing-operators-explained/https://ivankahl.com/blog/csharp-null-conditional-and-null-coalescing-operators-explained/C#'s null-conditional and null-coalescing operators handle null values gracefully, resulting in cleaner and more robust code. Each is explained with examples.Wed, 01 Jan 2025 00:00:00 GMTC#ProgrammingQuick TipGuideshttps://ivankahl.com/blog/introduction-to-mapster-in-csharp/https://ivankahl.com/blog/introduction-to-mapster-in-csharp/Mapster is a high-performance object mapping library for .NET. A beginner-friendly introduction highlights the key features behind efficient data mapping in C#.Mon, 03 Jun 2024 00:00:00 GMTGuides.NETTutorialshttps://ivankahl.com/blog/extension-methods-in-csharp/https://ivankahl.com/blog/extension-methods-in-csharp/Extension methods let C# developers add functionality to existing classes, even sealed third-party ones, without resorting to inheritance or wrapper classes.Mon, 21 Mar 2022 00:00:00 GMTC#.NET.NET 6.NET CoreGuideshttps://ivankahl.com/blog/case-sensitive-and-insensitive-string-comparisons-in-powershell/https://ivankahl.com/blog/case-sensitive-and-insensitive-string-comparisons-in-powershell/PowerShell offers separate operators for case-sensitive and case-insensitive string comparisons, such as -eq, -ceq, -like, and -clike. Each is explained with examples.Sat, 18 Dec 2021 00:00:00 GMTPowershellQuick TipGuideshttps://ivankahl.com/blog/logging-dotnet-to-aws-cloudwatch-using-nlog/https://ivankahl.com/blog/logging-dotnet-to-aws-cloudwatch-using-nlog/NLog can ship .NET application logs straight to AWS CloudWatch. This guide covers installation, CloudWatch configuration, and settings for better performance.Tue, 14 Dec 2021 00:00:00 GMT.NET.NET 6.NET CoreAWSAWS CloudWatchNLogTutorialshttps://ivankahl.com/blog/logging-dotnet-to-aws-cloudwatch-using-serilog/https://ivankahl.com/blog/logging-dotnet-to-aws-cloudwatch-using-serilog/Serilog can write .NET application logs to AWS CloudWatch. Setup, CloudWatch integration, and log settings for better performance are covered in detail.Sat, 11 Dec 2021 00:00:00 GMT.NET.NET Core.NET 6AWSAWS CloudWatchSerilogTutorialshttps://ivankahl.com/blog/logging-dotnet-to-aws-cloudwatch-using-awssdk/https://ivankahl.com/blog/logging-dotnet-to-aws-cloudwatch-using-awssdk/The AWS SDK can send .NET application logs directly to CloudWatch. Log groups and streams are created, and log messages are sent programmatically, step by step.Fri, 10 Dec 2021 00:00:00 GMT.NET.NET Core.NET 6AWSAWS CloudWatchTutorialshttps://ivankahl.com/blog/introduction-to-aspect-oriented-programming-in-dotnet-with-autofac-interceptors/https://ivankahl.com/blog/introduction-to-aspect-oriented-programming-in-dotnet-with-autofac-interceptors/Aspect-Oriented Programming improves modularity and readability in .NET. Autofac interceptors are set up and used to apply AOP principles in practice.Sat, 17 Jul 2021 00:00:00 GMTDependency Injection.NET Core.NETAspect-oriented Programming (AOP)TutorialsGuideshttps://ivankahl.com/blog/three-methods-to-convert-strings-into-enums-in-csharp/https://ivankahl.com/blog/three-methods-to-convert-strings-into-enums-in-csharp/Three methods for converting strings into enums in C# are compared, with guidance on which approach best suits different performance and safety requirements.Sun, 06 Dec 2020 00:00:00 GMT.NET Core.NETC#Guideshttps://ivankahl.com/blog/use-config-net-for-net-application-configurations/https://ivankahl.com/blog/use-config-net-for-net-application-configurations/Config.Net offers an interface-based way to manage settings in .NET and .NET Core applications with minimal boilerplate. A follow-up to the App.config article.Thu, 22 Oct 2020 00:00:00 GMT.NET.NET CoreProgrammingVisual StudioC#Tech TipsTutorialshttps://ivankahl.com/blog/the-comprehensive-guide-to-custom-datetime-string-formats-in-csharp/https://ivankahl.com/blog/the-comprehensive-guide-to-custom-datetime-string-formats-in-csharp/C# offers several ways to turn a DateTime into a string. Custom format specifiers give full control over the output, and each one is explained with examples.Sat, 13 Jun 2020 00:00:00 GMTC#.NET.NET CoreGuideshttps://ivankahl.com/blog/backing-up-and-restoring-native-sql-server-backups-in-aws-rds/https://ivankahl.com/blog/backing-up-and-restoring-native-sql-server-backups-in-aws-rds/Native SQL Server backups can be created and restored in AWS RDS once an S3 bucket and the right access are in place, as this walkthrough shows step by step.Thu, 20 Feb 2020 00:00:00 GMTSQL ServerAWSTutorialshttps://ivankahl.com/blog/getting-aws-lambda-environment-variables-in-all-supported-languages/https://ivankahl.com/blog/getting-aws-lambda-environment-variables-in-all-supported-languages/Every language supported by AWS Lambda reads environment variables through its own native API. Code snippets for each are collected in one place, with no extra dependencies.Tue, 29 Oct 2019 00:00:00 GMTAWSLambdaServerlessGuideshttps://ivankahl.com/blog/send-slack-messages-from-anywhere-using-webhook-integration/https://ivankahl.com/blog/send-slack-messages-from-anywhere-using-webhook-integration/A Slack bot with an incoming webhook can notify a team channel when a process fails. Setup is shown step by step, with Postman used to send a test message.Mon, 23 Sep 2019 00:00:00 GMTSlackIntegrationPostmanRESTTutorialshttps://ivankahl.com/blog/enabling-and-disabling-hyper-v-in-powershell/https://ivankahl.com/blog/enabling-and-disabling-hyper-v-in-powershell/Running VirtualBox or other virtualization software on Windows 10 often means turning Hyper-V off. Two PowerShell commands make enabling and disabling it quick.Wed, 27 Mar 2019 00:00:00 GMTWindowsPowershellhttps://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-5-a-word-on-authentication/https://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-5-a-word-on-authentication/The final part of the SData 2.0 series for Sage CRM, comparing the available authentication methods and when each one is the best choice.Thu, 21 Feb 2019 00:00:00 GMTSage CRMSDataSData 2.0IntegrationSecurityhttps://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-4-deleting-records/https://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-4-deleting-records/Part four of the SData 2.0 series for Sage CRM, showing how to delete records with the DELETE verb, using examples such as removing a company.Tue, 19 Feb 2019 00:00:00 GMTSDataSData 2.0Sage CRMIntegrationhttps://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-2-updating-records/https://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-2-updating-records/Part two of the SData 2.0 series for Sage CRM, showing how to update existing records with the PATCH verb and a JSON request body, using examples.Sun, 17 Feb 2019 00:00:00 GMTSage CRMSDataSData 2.0Integrationhttps://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-3-inserting-records/https://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-3-inserting-records/Part three of the SData 2.0 series for Sage CRM, showing how to insert new records with the POST verb, using examples such as creating a company.Sun, 17 Feb 2019 00:00:00 GMTSage CRMSDataSData 2.0Integrationhttps://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-1-introduction-and-querying/https://ivankahl.com/blog/using-sdata-2-0-in-sage-crm-part-1-introduction-and-querying/The first in a series on SData 2.0 in Sage CRM, introducing the RESTful API, how it differs from SData 1.1, and how to query records with Postman.Sat, 16 Feb 2019 00:00:00 GMTSage CRMSData 2.0SDataRESTIntegrationhttps://ivankahl.com/blog/smtp-imap-and-pop-settings-for-popular-email-providers/https://ivankahl.com/blog/smtp-imap-and-pop-settings-for-popular-email-providers/A quick reference of the SMTP, IMAP, and POP server addresses, ports, and security settings for popular email providers, handy for email integrations.Fri, 15 Feb 2019 00:00:00 GMTEmailhttps://ivankahl.com/blog/relicensing-sage-crm/https://ivankahl.com/blog/relicensing-sage-crm/Renewing or upgrading a client's Sage CRM license means relicensing the system. The short process is laid out step by step, along with its prerequisites.Tue, 08 Jan 2019 00:00:00 GMTSage CRMLicensehttps://ivankahl.com/blog/sage-crm-exchange-integration-sage-crm-setup/https://ivankahl.com/blog/sage-crm-exchange-integration-sage-crm-setup/Synchronizing contacts, appointments, and tasks between Sage CRM and Exchange/Office 365 starts with configuring the integration in Sage CRM, as shown here.Tue, 08 Jan 2019 00:00:00 GMTSage CRMIntegrationOffice 365Exchangehttps://ivankahl.com/blog/sage-crm-exchange-integration-office-365-setup/https://ivankahl.com/blog/sage-crm-exchange-integration-office-365-setup/Before Sage CRM can sync with Exchange, Office 365 needs a dedicated user and an impersonation role. The setup is covered step by step.Mon, 07 Jan 2019 00:00:00 GMTSage CRMIntegrationOffice 365Exchangehttps://ivankahl.com/blog/cannot-process-file-because-of-mark-of-the-web-error-in-visual-c-project/https://ivankahl.com/blog/cannot-process-file-because-of-mark-of-the-web-error-in-visual-c-project/A build error caused by the Mark of the Web can block Visual Studio projects. Several fixes are covered, from unblocking files to more obscure solutions.Sun, 06 Jan 2019 00:00:00 GMT.NETProgrammingC#Visual Studiohttps://ivankahl.com/blog/fixing-authentication-required-browser-session-mismatch-error-in-sage-crm/https://ivankahl.com/blog/fixing-authentication-required-browser-session-mismatch-error-in-sage-crm/Logging into Sage CRM over HTTPS with Internet Explorer can trigger a "Browser session mismatch" error. The cause and the fix are explained.Mon, 12 Nov 2018 00:00:00 GMTSage CRMSecurityhttps://ivankahl.com/blog/fixing-cannot-create-file-error-when-viewing-sage-crm-report-on-screen/https://ivankahl.com/blog/fixing-cannot-create-file-error-when-viewing-sage-crm-report-on-screen/A domain change can leave the Sage CRM application pool without file permissions, causing a "Cannot create file" error in reports. Granting access fixes it.Tue, 23 Oct 2018 00:00:00 GMTSage CRMReportshttps://ivankahl.com/blog/the-humbs-db-attachment-in-sage-crm-emails/https://ivankahl.com/blog/the-humbs-db-attachment-in-sage-crm-emails/A mysterious humbs.db attachment can get Sage CRM emails flagged as spam. Disabling thumbnail caching and removing existing attachments resolves it.Tue, 14 Aug 2018 00:00:00 GMTSage CRMEmailWindowshttps://ivankahl.com/blog/enabling-cors-in-nancy/https://ivankahl.com/blog/enabling-cors-in-nancy/A single line of code in a Nancy module enables CORS, allowing a REST API built with Nancy to be called from JavaScript hosted on other domains.Wed, 08 Aug 2018 00:00:00 GMTNancyCORS.NETC#Visual Studiohttps://ivankahl.com/blog/disabling-checkpoints-in-hyper-v/https://ivankahl.com/blog/disabling-checkpoints-in-hyper-v/Hyper-V's automatic checkpoints can slow down shutdowns and corrupt virtual drives when merging fails. Disabling them per virtual machine avoids the problem.Fri, 03 Aug 2018 00:00:00 GMTHyper-VWindowsVirtualizationVirtual Machineshttps://ivankahl.com/blog/fixing-class-not-registered-error-in-sage-crm-net-pages/https://ivankahl.com/blog/fixing-class-not-registered-error-in-sage-crm-net-pages/A July 2018 Windows update can break Sage CRM .NET pages with a "Class not registered" error. A small IIS authentication change resolves it.Wed, 01 Aug 2018 00:00:00 GMTSage CRM.NETIISWindows UpdateWindowshttps://ivankahl.com/blog/fixing-unexpectedevent-when-uploading-documents-in-sage-crm/https://ivankahl.com/blog/fixing-unexpectedevent-when-uploading-documents-in-sage-crm/Sage CRM document uploads can fail with an "UnexpectedEvent" error when document type codes are too long. The cause and the fix are explained here.Wed, 01 Aug 2018 00:00:00 GMTSage CRMDocument LibraryUnexpectedEventhttps://ivankahl.com/blog/fixing-credssp-encryption-oracle-remediation-in-rdp/https://ivankahl.com/blog/fixing-credssp-encryption-oracle-remediation-in-rdp/After the CredSSP security patch, RDP connections to unpatched servers fail with an encryption oracle error. A temporary registry change gets connections working again.Sun, 13 May 2018 00:00:00 GMTTech TipsWindowshttps://ivankahl.com/blog/sage-crm-net-templates-visual-studio-extension/https://ivankahl.com/blog/sage-crm-net-templates-visual-studio-extension/A Visual Studio extension speeds up .NET development for Sage CRM, bundling project templates, item templates, and snippets for commonly used components.Sun, 01 Apr 2018 00:00:00 GMTProgrammingSage CRMC#Visual StudioExtensionTemplatesVSIXhttps://ivankahl.com/blog/using-sql-server-cursors/https://ivankahl.com/blog/using-sql-server-cursors/SQL Server cursors process data one record at a time, much like a loop in code. A worked example imports companies and their people from a staging table.Sun, 01 Apr 2018 00:00:00 GMTSQL ServerSQLProgramminghttps://ivankahl.com/blog/converting-between-different-virtual-drive-formats/https://ivankahl.com/blog/converting-between-different-virtual-drive-formats/Moving a virtual machine between Hyper-V and VirtualBox often means converting its drive. StarWind V2V Converter handles VHDX to VHD conversion for free.Fri, 02 Mar 2018 00:00:00 GMTTech TipsVirtualizationVirtual Machineshttps://ivankahl.com/blog/using-reflection-to-execute-assemblies-at-runtime-in-c/https://ivankahl.com/blog/using-reflection-to-execute-assemblies-at-runtime-in-c/Reflection lets a C# application load DLL assemblies at runtime, extract methods from them, and execute those methods without compile-time references.Mon, 29 Jan 2018 00:00:00 GMT.NETProgrammingC#Visual Studiohttps://ivankahl.com/blog/creating-custom-configuration-sections-in-app-config/https://ivankahl.com/blog/creating-custom-configuration-sections-in-app-config/Custom configuration sections let a .NET app read structured settings from its App.config file. The classes needed to define and read them are demonstrated.Wed, 24 Jan 2018 00:00:00 GMT.NETProgrammingC#Visual Studiohttps://ivankahl.com/blog/python-virtual-environments-in-visual-studio/https://ivankahl.com/blog/python-virtual-environments-in-visual-studio/Python virtual environments keep project dependencies isolated, and Visual Studio makes them easy to manage. Creating and using them is covered step by step.Fri, 22 Dec 2017 00:00:00 GMTProgrammingPythonVisual Studiohttps://ivankahl.com/blog/python-list-and-dictionary-comprehensions/https://ivankahl.com/blog/python-list-and-dictionary-comprehensions/Python comprehensions build lists and dictionaries from existing data or generated sequences in a single readable expression, as these examples show.Sat, 02 Dec 2017 00:00:00 GMTPythonProgramminghttps://ivankahl.com/blog/app-review-pythonista/https://ivankahl.com/blog/app-review-pythonista/Pythonista brings a full Python editor and runtime to iPad and iPhone. A hands-on review of its code editor, custom keyboard, and other features for coding on the go.Fri, 22 May 2015 00:00:00 GMTApp ReviewsProgrammingPythonhttps://ivankahl.com/blog/blogs-up-and-running/https://ivankahl.com/blog/blogs-up-and-running/A short welcome to the blog, which was started to share thoughts, tutorials, and lessons learned on programming and other hobby-related topics.Thu, 21 May 2015 00:00:00 GMTGeneral